The El's "express" trains aren't really express. It's just a way to get a train back on schedule if it's been severely delayed for some reason. The system isn't

The El's "express" trains aren't really express. It's just a way to get a train back on schedule if it's been severely delayed for some reason. The system isn't set up for one train to be able to pass another, so it has to go back to regular service once it's back on schedule.